Ceramic parts for electrical devices having magnetic properties and method of making



Sept. 25, 1951 E. ALaERs-scHoENBERG 2,568,881

CERAMIC PARTS FOR ELECTRICAL DEVICES HAVING MAGNETIC PROPERTIES AND METHOD OF MAKING Filed Dec. 28, 1948 I lill FEAR/nr 608 y 37647775 Hilf IN VEN TOR.

. [anar faens- ScuaeA/aua Patented Sept. 25, 1951 CERAMIC PARTS FOR ELECTRICAL DEVICES HAVING MAGNETIC PROPERTIES AN METHOD F MAKING Ems: Alben-schwaben, Memoiren, N. J.,

signor to Steatite Research Corporation, Keasbey, N. J., a corporation of Delaware Application December 28, 1948, Serial No. 67,751

This invention relates to improvements in ceramic parts for electrical devices comprising materials having magnetic properties with insulating parts and the process of producing the same. i

An object of the invention is to produce magnetic bodies of ceramic material having improved electrical water resistance and other properties.

Another object of the invention is to provide magnetic bodies of ceramic material with a heat resistant insulating coating.

Another object of the invention is to provide magnetic bodies of ceramic material which are stable at high temperatures and which have a heat resistant insulating coating.

Another object of the invention is to provide a composite ceramic article containing one or more sections made of insulating material, one or more sections made of ceramic magnetic material and one or more sections of insulating material having a high K value.

Another object of the invention is to provide a composite ceramic article containing one or more sections made of insulating material, one or more sections made of ceramic magnetic material and one or more sections of insulating material having a high K value, said sections" being united by a heat resistant ceramic glaze.

These and other objects are obtained by coating a ferromagnetic ceramic bodyof the ferrite type with a. ceramic glaze (slip) and curing the glaze to produce a ceramic magnetic object with a water proof, non-porous, attractive insulating coating. The ceramic magnetic material may be united with other ceramic materials such as steatite for insulating and/or titania or titanate bodies having high K-values, by the applied glaze. Preferably the ferrite magnetic body is first matured before applying the glaze because if the raw body would be fired together with the glaze a reaction would occur between the components of the glaze and the adjacent ferric oxide of the ferrite body.

The term ferromagnetic ceramic body of the ferrite type is intended to include the magnetic materials of the formula M"O.Mz"'0a in which M" is a divalent metal and M'" is a trivalent metal of the group consisting of iron, cobalt, and

7 Claims. (Cl. 154-428) In preparing the composite articles having parts made of magnetic ferrite material and parts made of insulating material such as steatite or materials with a high dielectric constant (such as the titanates and titanium dioxide), the separate parts are first finished separately by molding, firing and if necessary grinding. The combined article is then ass'embledand united by glazing the adjacent surfaces together. To unite the parts by glazing the surfaces of contact of the parts are first painted with the glaze-slip, the parts are put together and held tightly and then dried and tired. The melting glaze knits the pieces together at the contacting surfaces. Thus parts can be made which consist partly of magnetic insulating material. partly of ordinary insulating material and/or partly of a high K-dielectric condenser body. In the whole they are to be considered as ceramic parts showing invariability of shape Within any reasonably desired range of temperature. As examples of the useful articles made according to the invention, there may be mentioned ilat pieces carrying printed circuits, steatite-bases with glazed on cores, rods of magnetic materials or ferromagnetic shielding tubes glazed together with insulating bases, etc.`l

In the drawing Figure 1 is a perspective view of a combination block made up of three sections.

Figure 2 is a view partly broken away of a compound block of two sections with a glaze uniting and covering the sections.

Figure 3 is a perspective view of a ferrite core material united to a steatite base by a glaze.

As shown in the Figure 1 of the drawing a ceramic insulating block Ill which may be steatite for example may be united to a ferrite block Il by means of glaze layer I2 and a ceramic material with a high K value I3, such as steatite to which barium titanate has been added, may be united to the ferrite block I2 by the layer of glaze I4.

As indicated by Figure 2, the glaze layers 20-22 may extend over the whole surface of the blocks 23 and 24 which the layer 25 serves to unite.

Figure 3 shows a ferrite core material 30 united t; an insulating base 3| by means of glaze layer Example 1 A ferrite body is made by mixing of powdered FezOa, 7% MgO, 10% MnOz and 8% of ZnO with just enough water and plasticizer to make a paste or pressing granulation. This body is molded to form one complementary part of the linished article and red at about 1200 C.

Powdered steatite is mixed with 10 to 15% of asoaesi powdered clay and feldspar or barium carbonate and enough water to make a paste or pressing formulation and this paste is molded to the shape of the second complementary part of the finished article and fired at 1300 C.

A glaze-slip having a maturing temperature of 9001000 C. is made having the following composition:

Water to proper consistency The glaze slip is painted on the surfaces to be joined. The pieces are assembled in the proper position, clamped in position, and then the article is dried and fired at the maturing temperature oi' the glaze.

Example 2 A ferrite core for an inductive coil is made by mixing 77% of powdered FezOa and 14% of powdered NiO and 9% of powdered MgO. The mixture is molded to form the core material and is fired at about 1200 C.

This core which is slightly porous is thereafter completely coated with a glaze slip similar to the above mentioned, and fired at about 900 C.

The nal fired product has a smooth, transparent, insulating coating which is heat resistant within any reasonably desired range of temperatures and which is non porous and water resistant.

I claim:

1. A shaped and ilred ferromagnetic ceramic body of the ferrite type having a ceramic glaze capable of maturing at a temperature of less than 1000 C. covering and protecting the exposed surfaces thereof.

2. A ceramic body containing at least one section of ferrite material and at least one section of a molded ceramic insulating material the said sections being united at their contacting areas with a ceramic glaze capable of maturing at a. temperature of less than 1000 C.

3. A ceramic body containing at least one section of ferrite magnetic ceramic material at least one section of a molded ceramic insulating material having a high K-value, the said sections being united at their contacting areas with a ceramic glaze.

4. The process of making a composite article adapted as a base plate for electrical circuits comprising the steps of molding and firing a ferrite magnetic ceramic part, molding and firing a ceramic insulating part, molding and firing a ceramic insulating part having a high K-value, applying a glaze slip having a maturing temperature which is less than 1000 C. to complementary areas of the fired ceramic parts, placing the parts together in the shape of the desired finished article, clamping the parts together and drying and firing the article at the maturing temperature of said glaze to unite the parts.

5. The process of making a composite article adapted as a base plate for electrical circuits comprising the steps of moldingv and firing a ferrite magnetic ceramic part, molding and firing a ceramic insulating part having a high K-value, applying a glaze slip having a maturing temperature of less than 1000 C. to complementary areas of the fired ceramic parts. placing the parts together in the desired way and drying and firing said article at the maturing temperature of said glaze while holding said parts together to unite the parts.

6. The process of making a composite article adapted as a base plate for electrical circuits comprising the steps of molding and tiring a first ceramic part formed of ceramic insulating material and having at least one surface area adapted to coincide with and be united to a similar surface area of a second part, molding and firing a second ceramic part formed of a ferromagnetic ceramic ferrite and having at least one surface area adapted to coincide with and be united to said surface area of the rst part, grinding the corresponding area of at least one of the two parts to provide a smooth fit, applying a ceramic glaze slip having a maturing temperature below 1000 C. and below that which deleteriously affects said fired parts to the said areas of the parts to be united, placing said parts together so that the said corresponding areas coincide and drying and firing said article at the maturing temperature of said glaze while holding the said parts together whereby said parts are united by the matured glaze.

7. The process of making a composite article adapted as a base plate for electrical circuits comprising the steps of molding and firing a first part formed of ceramic material and having at least one surface area adapted w coincide with and be united to a similar surface area of a second part, molding and firing a second part formed of ceramic material and having at least one surface area adapted to coincide with and be united to said surface area of the first part and at least one different surface area adapted to coincide with a surface area of a third part, molding and firing a third part formed of ceramic material and having at least one surface area which is adapted to coincide with the surface area of the second part, grinding at least one of said areas which is adapted to be united to an area of another part to provide a smooth fit, applying a ceramic glaze slip having a maturing temperature below 1000 C. and below that which deleteriously affects said flred parts to the said areas of the parts to be united. placing said parts together so that the said corresponding areas coincide and drying and firing said article at the maturing temperature of said glaze while holding the said parts together whereby said parts are united by the matured glaze. one of said parts consisting essentially of a ceramic insulating material, another of said parts consisting essentially of a ceramic ferromagnetic ferrite material. and another of said parts consisting essentially of a ceramic insulating material having a high K- value. l

ERNST ALBERS-SCHORNBERG.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,164,739 Mershon Dec. 2l. 1915 2,056,069 McCoy Sept. 29. 1938 2,321,983 Mayer Nov. 19, 1940 2.262.831 Burleson Nov. 18. 1941 

2. A CERAMIC BODY CONTAINING AT LEAST ONE SECTION OF FERRITE MATERIAL AND AT LEAST ONE SECTION OF A MOLDED CERAMIC INSULATING MATERIAL THE SAID SECTIONS BEING UNITED AT THEIR CONTACTING AREAS WITH A CERAMIC GLAZE CAPABLE OF MATURING AT A TEMPERATURE OF LESS THAN 1000* C.
 4. THE PROCESS OF MAKING A COMPOSITION ARTICLE ADAPTED AS A BASE PLATE FOR ELECTRIC CIRCUITS COMPRISING THE STEPS OF MOLDING AND FIRING A FERRITE MAGNETIC CERAMIC PART, MOLDING AND FIRING A CERAMIC INSULTING PART, MOLDING AND FIRING A CERAMIC INSULATING PART HAVING A HIGH K-VALUE, APPLYING A GLAZE SLIP HAVING A MATURING TEMPERATURE WHICH IS LESS THAN 1000* C. TO COMPLEMENTARY AREAS OF HE FIRED CERAMIC PARTS, PLACING THE PARTS TOGETHER IN THE SHAPE OF THE DESIRED FINISHED ARTICLE, CLAMPING THE PARTS TOGETHER AND DRYING AND FIRING THE ARTICLE AT THE MATURING TEMPERATURE OF SAID GLAZE TO UNITE THE PARTS. 